Studies On Oncogene And Tumor Suppressor Gene In The Plasma And The Tumor Tissue From Pancreatic Cancer Patients

Pancreatic carcinoma(PC) is a dismal disease with increased morbidity. One important cause of the poor prognosis is that we have no sensitive and specific tumor markers, which makes diagnosis rather difficult. 'Major advances in the field of molecular biology about PC have been made recently. It has been reported that genetic alterations were found during the development of pancreatic carcinoma. Point mutation in K-ras gene at codon 12 may be frequently detected in the PC tissues, pure pancreatic juice, plasma, et al. Detection of p53 mutations is useful for diagnosis and prognosis prediction of PC. The aim of this study is to investigate the value of these abnomalities in the diagnosis of PC using the technique of oligonucleotide microarray (oligomicroarray).Materials and methods: 25 patients with PC and 5 patients with chronic pancreatitis were selected. We first extracted the cell-free DNA fragments in plasma and genomic DNA from tumor tissue. Then we analyzed mutations in K-ras gene at codon 12 and p53 gene in exon 5 and exon 7.Results: 1. The positivity of K-ras point mutation in tumor tissue was 76.0%(19/25) in patients with PC, and the positivity in plasma was 52.0%(13/25). Both were found in the early stage of PC. The mutations of K-ras gene were mostly found at codon 12. At the same time, CA19-9 measurement was performed. The positivity of the detection combined K-ras mutations and CA19-9 was significantly higher than single K-ras mutations.2. The positivity of p53 gene point mutation in tumor tissue was 32.0%(8/25) in patients with PC, and the positivity in plasma was 20.0%(5/25). Both correlated with the stage of PC. There were not hotpots in the mutations of p53 gene. The mode of mutations mostly was transition(GC-AT). Using a combination assay with both genes, genetic abnormalities were detected in 92%( 23/25) of patients with PC. The specificity of p53 mutation for PC was very high.Conclusions: Simultaneous analysis of K-ras and p53 mutation is suggested to enhence the genetic diagnosis of PC. The technique of oligonucleotide microarray is a simple and convenient, sensitive, effective, reliable method to detect gene mutations, which is worthy of being popularized..